Federal agencies have increased Columbia River flows below Bonneville Dam to ensure nests holding chum salmon eggs stay covered with water.
The U.S. Army Corps of Engineers, which owns and operates the dam, manages flows so the river is 11.5 to 13 feet above sea level to ensure chum can spawn at the mouth of Hamilton Creek.
Water is released from reservoirs as far away as Hungry Horse and Libby dams in Montana, more than 850 river miles from Bonneville Dam. Federal agencies have conducted these chum operations every fall since 2000.
“Chum are listed under the federal Endangered Species Act, and they’re an important part of the ecosystem,” Scott Armentrout, Bonneville Power Administration’s vice president for environment, fish and wildlife, said in a statement. “This operation is just one of the things we do with our federal partners to support this critical species.”
The annual run of Columbia River chum salmon historically numbered more than 1 million. Habitat loss, fishing and other factors caused their numbers to plummet during the past century to a low of just a few thousand fish returning each year.
Chum salmon were listed as threatened under the Endangered Species Act in 1999.
Called “dog” salmon because of their canine-like teeth, chum are the last salmon of the year to return to the Columbia to spawn, and their offspring are the first to leave for the Pacific Ocean in the spring.
The Bonneville Power Administration has funded two hatchery programs and constructed spawning habitat for chum in several areas of the lower Columbia River.
These efforts appear to be showing signs of success. More than 45,000 chum returned to the Columbia in 2016, and scientists say 2019 shows signs of a good return as well.